Energy grass a good thermal option in Vermont, the Northeast

A new report published by Wilson Engineering on behalf of the Vermont Bioenergy Initiative explores the potential of growing and harvesting energy grasses for thermal energy in Vermont.

In the paper, four different grass energy project models are evaluated and compared, including in-depth analysis of advantages and disadvantages of each. In a closed-loop model with no processing, the crop is grown on local acres and baled on stored on site, then later burned at locations with adequate thermal loads such as a school or hospital.

Using a small-scale, on-farm processing model, the crop is again grown on local acres and baled and stored on-site, but a small stationary or mobile pelletizer is used to process grass bales into pellets, cubes or briquettes, which are then sold to local markets.

In a regional processing model, a central processing plant would purchase baled hay from local farmers and then grind, dry and densify the grass into cubes, briquettes, or pellets and deliver fuel to multiple commercial or institutional thermal installations.

Finally, using a consumer pellet market model, a central processing plant would produce a standardized pellet for use in installed pellet stoves, furnaces and boilers.

The report finds that out of the four models, small-scale, on-farm processing has the greatest challenges due to the complexity of the process and the overall inefficiencies of densifying grass energy on a small scale, and that closed-loop, no-processing model would be the easiest to implement in Vermont, as minimal investment is required in harvesting and processing.

The regional processing model, which matches specific thermal installations to processing capacity, would also make sense for Vermont, indicates the report, which continues on to detail the benefits energy grass offers in Vermont, including lower fuel costs, improved economic and energy security and reduced carbon emissions, increased productivity on marginal lands, permanent cover on highly erodible lands and removal of nutrients to reduce and clean up run-off from farms and developed landscapes.

Millions of acres of idle and marginal lands in the Northeast are conducive for growing these energy crops, according to the report, and as the market for bioenergy products develops, they—switchgrass and miscanthus in particular—could provide an important source of material for heat, fiber or liquid fuels like cellulosic ethanol.

The report also provides general information on, comparisons of and supplier information of switchgrass and giant miscanthus, as well as densification and thermal combustion testing.